Blasting cartridge



aeuted t. i3, f2...

la fESTBNG, F CHICAGO, ILLDTOIS, .i i"

Pm, 0F CHICAGO, 14915, A GQQTIO appuaaoa mea www 7, new. serial m. seam.

The present invention relates to blasting v `cartridges of the t pe which consists of a metallic shell or bo y having an internal gas chamber, a pressure responsive discharge de- Y -vice and charging and charge energizing means. The latter m'eans usuall conslsts of l a heat producing unit disposed within the gas chamber and arranged to be electrically activated, and for this purpose, the heaterY unit is arranged in circuit with the shell body and an electrode suitably insulated from the body. The gas charge may be introduced through a valve controlled passage in the electrode. Inorder to operate a cartrid e l of this character, the electrode and shell bo y are placed in circuit with a source of electricyThe general object of this invention is to simplify the construction of cartridges of the 2@ type indicated with a view to securing increased reliability and minimizing service requirements.

More particularly, it is an object of the invention to provide an improved form of 25 support for the heater unit, and an improved means of including the heater unit in circuit with the electrode and shell body.

' Another object of the invention is to pro-p vide an improved means for connecting the electrode and shell body in circuit w1th a source of electricit Other objects and, advantages of the invention will be noted in the following description of the accompanyin drawin wherein,

Figure 1 is aview in e evation s owing the form of the assembled cartridge.

Figures 2 and 2A are views 1n lon 'tudinal section, together showing the comp ete cartridge of the present invention, and

Figure 3 is a view in transverse section taken along line 3-3 of Figure 2.

The cartridge of the present invention consists generally of a substantially cylindrical body 1 having an internal as chamber 2 which is open at one end o the body for discharge purposes. ,A rupturable disc 3 formed of mild steel or the like is employed .to seal the discharge openin and for this purpose a shoulder 4 is provi ed in the shell 5o body on which the disc is adapted to rest.

The disc is backed u by an anvil or shear ring 5 formed of har steel and this ring is secured in place by means of the discharge cap 6 which is screw threaded into the end of the cartridge bod and has its end in engagement with the s ear ring. The dischar ev cap is rovided with an axial passage 8 an a plurahty of radial discharge ports 9.' The cartridge so formed is adapted to be charged with a suitably compressed gas and may'be discharged by means of a heat producin device capable of increasing the pressure o the gas charge to the rupture point of the disc'3. The opposite end of the gas chamber 2 is defined by a transverse wall 10 which is rovided with a central opening through w ich an electrode element 11 is positioned. nwardly of the .wall 10 there -is formed asubstantially cylindrical pocket 12 which communicates with the gas chamber and a portion of which is screw threaded as indicated at 13. The electrode 11 is provided withva liange 14 which is adapted to be position within the pocket 12 and to be clamped in such osition by means of a nut surrounding t e reduced inner end of the electrode and engaging the inner face of the iange. rlhe nut. 15 is adapted to engage threads 14 formed in the cartridge body in order that a considerable pressure may be applied to the electrode in an axial direction to provide an eective seal between the radial surface of the ilange` 14 and the adjacent surface of the wall 10. The nut 15 is formed intermediate. its ends with hexagon or other suitable surfaces to receive a wrench or the like for tightening the nut. The extreme inner end o the nut 15 is sufliciently reduced in diameter to permit `the application of a socket wrench thereover andl this reduced portion is preferably provided with screw threads as indicated at 17 to. receive and support a heater cage 18. It will be observedV that an end of the heater cage 18 is screw threaded for. engagement. with the thread formed on the inner end of the electrode nut." The heater ca e isthussupportedandextend.

axially into t e gas chamber 2, but as will be seen in Figure 2A, the cage terminates short of the discharge opening in the end of im the'cartridge. rlihe -J'Eorm of the heater cage is best shown in Figures 2, 2A and 3 wherein it will be observed that the tube of which the cage is formed is provided with a plurality of elongated slots extending throu hout a substantial portion of the length of t e cage. rlhe end oie the cage remote from the electrode nut is partly closed by means of an inner sleeve which may be welded or otherwise securely fastened to the cage proper. rEhe sleeve 20 andthe end ot' the cage with which it is associated, are so formed as to provide a conical end depression to facilitate the entering of a suitable turning tool. i rlhe tool may be in the form of a pin wrench and for this purpose the end of the cage 18 and sleeve 20 are provided withy slots to accommodate the pins. ln order to facilitate the assembly of the heater cage upon the electrode nut, the inner endv of the nut is of conical form and the extreme end of the heater cage is also tapered inwardly in order that the heater may engage the end of the nut and automatically lind its proper position thereon. rlhe internal diameter of the heater cage is such that when the 'cage is resting on the inner wall of the gas chamber, the eXtreme inner end of the tapered portion of the electrode nut will lie within the end ot the heater cage. By reason of this construction, it is merely necessary to move the heater cage longitudinally within the gas chamber and it will automatically engage the tapered surface of the nut and ride upwardly thereon until it becomes properly centered, at which time the cage may be rotated in order to engage the threads thereof with the threads of the nut.

.at heater unit adapted for use in connection with the present heater cage and electrode is shown in the 'pending application in the name of L. E. Lawson, erial No. 373,- 016, tiled d une 22, 1929. structurally this heater unit comprises a tubular casing 21 which may be formed of paper or other suitable combustible material and metallic end closures 22 and 23. It will be noted that the closure 22 is applied over the end of the tube 2l whereas closure 23 is positioned entirely within the opposite end of the tube 21. These closures are preferably glued in place after the heater unit has been charged with the heat producing compound. It is to be understood, of course, that'a suitable elec-v tricall operated igniting device is em bedde in the heat producing compound of theheater and has its leads connected to the metallic closures 22 and 23. lt will be noted that the heater unit can be inserted through one end only of the heater cage and that when a heater has'been so inserted and the cage secured upon the electrode nut the metallic closure 22 has contact with the metal sleeve 2O and the metal of which the heater cage is formedand closure 23 surrounds and has contact onl with the inner end of the electrode 11. ttention is directed to the fact that by reason of the construction and I arrangement of the closure 23 with reference to the non-metallic heater casing, it is impossiblefor this closure to make contact with any portion of the cartridge except the electrode. There is, thus, a circuit from the electrode through the heater to the heater cage and consequently to 'the electrode nut and the body of the cartridge with which it is engaged. lt will he understood, or course, that the electrode ll is suitably insulated from the body of the cartridge and from the electrode nut as by means of insulating members 24, 25 and 26.

For the purpose of charging the cartridge with a suitable gas, the electrode is provided with an axial gas passage 34 which communicates with a transverse passage 35, leading into the gas chamber 2. A valve body 27 1s screw threaded on the outer end of the electrode and is insulated from the body of the cartridge by means of the fibre disc 28. A suitable nozzle opening 29 is provided in the valve body 27 and this opening has communication with a passage 30 leadin .to the in# terior of the valve body. A va ve stern 3l is adjustably engaged as by means of screw threads with the central portion of the body and carries a soft metallic insert 33 for cooperation with the valve seat 32 surrounding the gas passage in the outer end of the electrode. By means of this construction a charging nozzle may be inserted in the opening 29 ice and by screwing the valve stem 3l outwardly to remove the inner end thereof from engagement with the electrode, gas is permitted toV enter the interior of the valve body and pass through the electrode into the chamber 2. When the desired amount of gas has been charged into the cartridge the valve stem 3l may be tightly screwed down into engagement with the end of the electrode to positively seal the passage therein and thus prevent escape of the charge. In order to avoid accidental discharge of the cartridge by stray electric currents or by accidental contact of the cartridge with power lines or the like, a device is provided whereby the electrode and cartridge body are effectively short circuited until such time as the cartridge has reached its destination where it is to be discharged. This device consists of a plurality ofsharp knife edge contacts 36 formed on the under `side of the valve body and a sleeve 37 having an inwardly extending flange adapted to engage these contacts. The valve body is,\o'r" course, in electrical contact with the electrode only and the sleeve 37 is normally in electrical contactonly with the cartridge body through the medium of a metallic spring 38 which has one of its ends in engagement with the body and its opposite end in engagement with the inwardly extending flange of the sleeve. This of a source o cartridge body respectively and operating' I regatta the short circuiting device. This plug 39 has a detachable connection with'the end of the cartridge body which is in the form of lugs and bayonet slots as indicated at 40 and 4l. It will be observed from Figure 2 that the inner end of the plug isadapted to engage the end of sleeve 37 and move the sam'e inwardl to a suiiicient extent to break the contact etween the oints 36 and the iiange of the sleeve when t e plug is positioned 1n the cartridge. The plug is provided with an opening 42 designed to receive a suit-able conductor which may be secured in position b means of a set screw or the like as shown. metallic plug 43 is centrally positioned within a recess formed in the ring plug 39 but is insulated therefrom by means of the fibre disc 45 and fibre ring 44. The metallic plug 43 is provided with 'a central opening designed to receive a second conductor which may be secured therein by means of a set screw. A metallic spring 46extends between and electrically connects the plug 43 and the valve body 27. ln this way the poles of a source of current may be readily connect/ed to the electrode and cartridge body.

Heretofore, cartridges of this general type have relied upon the establishment of electrical contact between opposite ends of the heater unit and the electrode and rupturable disc respectively. This method of including the heater unit in 'circuit with the electrode and cartridge body has proven to be somewhat troublesome and ineiiicient due to the 'fact that the distance between the electrode and the rupturable disc is precisely vthe same in all cartridges of a given type, whereas it has been found in practice that the heater units vary considerably in length. Also, there has been some diiiiculty due to a poor contact or lack of contact between the rupturable disc and the adjacent end ofthe heater. Iihe present arrangement of the heater and supporting cage therefor is regarded as an yimportant improvement over the old method in that the heater need not be made of sucient length to extend the entire distance from the electrode 'to the rupturable disc, and may therefore be made oi any desired diameter to accommodate the amount of heat producing compound required. The present arrangement has also been found very advantageous in that both contacts ot the heater are in effect made adjacent the same end of the cartridge. in other words, one end ot the heater contacts with vthe electrode and the other end thereof has electrical connection with the electrodenut which immediately surrounds the electrode and connects with the cartridge body adjacent to the elecfrode. It will be noted that the heater cage may be so adjusted upon the threaded portion of the electrode nut as to accommodate substantial variations in heater dimensions,

thus insuring contact in all cases and without danger of disrupting the heater tube or damaging its contacts. e

I claim: f

1. A blasting cartridge comprising a metallic bod having an internal gas chamber, an electro e extending through an openin in said bod and into said chamber, a mem er surroun ing said electrode within the chamber and havin connection with said body, means for insu ating said electrode from saidbody and member, and an electrically enerizable heater unit having terminals connecting with said electrode and member respectively. y

2. A blasting 'cartridge comprisin ametallic body having an internal gas c amber, an electrode extending throughan opening in said body and into said chamber, a member surrounding said electrode within said chamber and having connection with said body, means for insulating said electrode from said body and member. a heater page supported by said member, and an electrically energizable heater unit disposed within said cage, said heater unit having terminals connecting with said electrode and cage respectively.

3. A blasting cartridge comprising a substantially cylindrical metallic 4body having an internal gas chamber, a pressure responsive discharge device associated with one end of said body, an insulated electrode associated with the other end of said body, an electrically energizable heater disposed within said chamber and having contacts, one of which is adapted to have electrical connec- 4. A blasting cartridge comprising a metallic body having an internal gas chamber,

an electrode associated with one end of said body and insulated therefrom, a heater unit having contacts, and ,means for connecting said contacts with said electrode and body respectively at said end.

5. A blasting cartridge comprising a metallic body having an internal gas chamber, a pressure responsive venting device associated with said body and chamber at one end thereof, an electrode extending through said body and into-said gas chamber adjacent the opposite end thereof, means for insulating said electrode froml said body, a nut surrounding said electrode and having threaded engagement with the interior ot said body, means its aaa

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for insulating said nut from said electrode, av

heater support secured to said nut, and a heat` er carried by said support and havlng elec trical contact at its'opposite ends with said eiectrode and heater support respectively,

6. biasting cartridge comprising a metailic body having an internal gas chamber, said body having a circular opening through a Wali thereof and a cylindricai` pocket adiacent said opening on the interior ot' said body and communicating with said chamber, an eiectrode positioned in said opening and extending on opposite sides of said Wall, a radial iange on said electrode and disposed Within said pocket, an insulating and seaiing member interposed between the end wal of said pocket and one face of 'said fiance, means surrounding said electrode and insulated therefrom and acting against the other face of said iange for effecting the seated reiation, a hea support carried by said means, and a heater carried by said sup- 1 port and having electricai contact with said eiectrode and support respectively. l

'a'. l.. blasting cartridge comprising a metallic body having an internal gas chamber, an electrode extending through a Wall oia said body and into said chamber, insulating means between said electrode and body, a gas passage extending through said electrode, a valve cap secured to the outer end of said electrode, a valve carried by said cap and adapted to cooperate 'ivith said passage, and a inovble member having electrica-l connection with said body and adapted to normally engage said cap to provide a short circuit bet-Ween said electrode and body.

8. A, blasting cartridge comprisingI a metallic body having an internal gas charnber, an electrode extending through a wall-of said body andinto said chamber, insulating means between said electrode and body, a gas passage extending through said electrode, a valve cap secured to the outer end of said electrode, a valve carried by said cap and adapted to cooperate with said passage, and a movable member having electrical connection with said body and adapted to normally engage said cap to provide a short circuit between said electrode and body and a detachable'plug having means for connecting saidv electrode and body respectively with the respective poles of a source of current and operable' when applied to break said short circuit.

9. A blasting cartridge comprisin a metallic body having an internal gas c amber, an electrode extending through a Wall of said body and intosaid chamber, insulating means between said electrode and body, a gas passage extending through said electrode, a valve cap secured to the outer end of said electrode, a valve carried by said 4cap and adapted to cooperate With said passage, a plurality of relatively sharp contact elements on said cap,

' an electrode extending aeaaaea a'mcnaoie member haviiisTq eiectricai connection with `said bodyv and' adapted to normally engage said contacts to provide a short vcir- 'cuit between said electrode and body, and 1 means for-breainngtne' short circuit.

i0'. A blasting cartridge comprising a metalii'c-.bodv having i tei-nai gas chamber, t trough a wall of said body and into said chamber, insuiating means between said eiectrode body, a gas passageextending thrusaid eiectrode,a Valve cap secured to the outer end of said eiectrode, a valve carried by said cap and adapted to cooperate with said passage, a piuraiity of relatively sharp contact cien/lents on. said cap, a sleeve surrounding said cap and having an ,inwardiy extending iange adapted to engage said contacts, a, spring interposed between said flange and the body *for norniaiiy urging said iange toward said contacts, and a plug having detachable engagement with said body and adapted to engage and move said sieeve out of contacting position.

if.. A blasting cartridge comprising a metaliic body having an internai gas chamber, a pressure responsive venting device associated with said body and chamber at one end thereof, an electrode extending through said body and into said gas chamber adjacent the opposite end thereof, means for insulating said electrode from said body, a nut surrounding said electrode and having threads on one end for engagement With the interior of said body, means for insulating said nnt from said electrode, said nut having threads on the opposite end thereof, a heater support engaging said threads, and a heater carried by said heater support and having electrical contact with said support and electrode, respectively. 12. A; blasting cartridge substantially as set forth in claim ll, further characterized in that said nut is provided with a Wrench engaging portion intermediate the threads on opposite ends thereof.

Signed at Chicago, illinois, this rd day of October, 1929.

FRANK H. ARMSTRONG.

Cook County, 

